DESCRIPTION: Virtually all eukaryotic organisms appropriately examined have[unreadable] been shown to possess the capacity for endogenous temporal control and[unreadable] organization known as a circadian rhythm. The cellular machinery[unreadable] responsible for generating this ability is collectively known as the[unreadable] biological clock. A healthy circadian clock underlies both physical and[unreadable] mental health. Because of the ubiquity of its influence on human mental and[unreadable] physiological process - from circadian changes in basic human physiology to[unreadable] the clear involvement of rhythms in work/rest cycles an sleep -[unreadable] understanding the clock is basic to prevention and treatment of many[unreadable] physical and mental illnesses.[unreadable] Our specific aims are designed to further our understanding of the means[unreadable] through which the clock regulates cat behavior in a tractable and well tuned[unreadable] model system and eventually in mammals. In previous work we show that the[unreadable] frequency gene encodes central components in the feedback loop comprising a[unreadable] circadian clock.[unreadable] We have determined that regulation of the expression of frq represents a[unreadable] major control point where external factors converge to affect the[unreadable] oscillator. In Specific Aim 1 we will study how transcriptional regulation[unreadable] of frq is effected. We will study proteins known to be required forfrq[unreadable] expression, appraise the importance of naturally occurring antisense frq[unreadable] transcripts, and execute a genetic screen to identify factors affecting frq[unreadable] expression. ->We have shown that the FRQ proteins are regulated both[unreadable] through synthesis and through modification, factor important in determining[unreadable] the kinetics of the clock cycle. In Specific Aim 2 we will study what[unreadable] regulates FRQ translation and how this responds to external factors[unreadable] including temperature. We will study FRQ phosphorylation, the relationship[unreadable] between phosphorylation and turnover, and will look for proteins with which[unreadable] FRQ interacts. We have established that the FRQ polypeptides are central[unreadable] components of the feedback loop comprising the clock. In Specific Aim 3 we[unreadable] will begin to analyze what FRQ regulates and both where and how it works.[unreadable] [unreadable] [unreadable] [unreadable] Our long term goals are to describe, in the language of genetics and[unreadable] biochemistry, the feedback cycle comprising the mechanism of the circadian[unreadable] clock, how this cycle is synchronized with the environment, and how tin[unreadable] information generated by the feedback cycle is used to regulate the behavior[unreadable] of cells. These projects a complementary and mutually enriching in that[unreadable] they rely on genetic and molecular techniques to dissect, and ultimately to[unreadable] understand. the organization of the cells as a function of time.[unreadable]